1. Field of the Invention
The invention relates to telecommunications. More particularly, the present invention relates to service signaling being processed in a controller adjunct to a switch.
2. Acronyms
The written description provided herein contains acronyms which refer to various network services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description herein, the acronyms are defined as follows:                Advanced Intelligent Network (AIN)        Asymmetric Digital Subscriber Line (ADSL)        Asynchronous Transfer Mode (ATM)        Broadband Services Network (BBSN)        Customer Premise Equipment (CPE)        Digital Subscriber Line (DSL)        FTTC (Fiber To The Curb)        Integrated Services Digital Network (ISDN)        Internet Protocol (IP)        Inter Network Interface (INI)        Interworking Function (IWF)        ISDN User Part (ISUP)        Lightweight Directory Access Protocol (LDAP)        Local Area Network (LAN)        Operations, Administration, & Maintenance (OA&M)        Permanent Virtual Circuit (PVC)        Personal Computer (PC)        Public Switched Telephone Network (PSTN)        Private Network to Network Interface (PNNI)        Proxy Signaling Agent (PSA)        Quality of Service (QoS)        Signaling System 7 (SS7)        Switched Virtual Circuit (SVC)        User to Network Interface (UNI)        Virtual Channel Identifier (VCI)        Virtual Network (VN)        Virtual Path (VP)        Virtual Path Identifier (VPI)        Virtual Path Connection Identifier (VPCI)        
3. Discussion of Background Information
High bandwidth ATM systems are in many cases replacing narrowband systems. As part of the migration to high bandwidth technologies, the efficient implementation of middleware services such as session management, messaging, directory, accounting, security, nomadicity, and database access are becoming problematic. In most ATM implementations, service related tasks are handled by transport layer systems using call models and triggers applied directly to transport layer devices, hindering the use and management of high bandwidth services.
A call model provides a template for the flow of service logic. Service definitions that do not fit the pre-defined flow are difficult, if not impossible, to implement in an intelligent network layer as is needed by broadband networks due in large part to the limited functionality of call models utilizing only triggers. To overcome some of the call model limitations, service nodes have arisen to provide services that do not fit current call models. But service nodes also have limitations when applied to broadband networks.
Alternative designs which entail signaling to a transport element, and then have the transport element “trigger” or signal to a network element for policy management decisions have enabled more service functionality; however, triggering is very costly due to additional software development costs and low functioning standardization. Moreover, such standardization typically requires additional signaling schemes between transport elements and network elements and modification of the flow of processing in the transport elements. The result being that transport elements eventually become a bottleneck in the deployment of new services because they must be updated with the new protocols and “call model” modifications as each new service is rolled out. In such an environment, the likelihood increases that switches from different vendors do not implement the same call model or protocol options and additional costs are incurred to handle different interfaces.
Because of the growing network demands of broadband networks, a new approach is needed that is of relatively low cost and more flexible than today's call model and trigger systems. An approach that separates service control from transport elements and allows service signaling directed to broadband network control elements would help satisfy these needs.
An example where a new approach to handling service signaling is needed is in the implementation of the Internet Protocol (IP). In various forms of IP traffic, service signaling, policy implementation, and data transport are handled together, and typically by the same device such as a router or firewall. Processing solely in the transport device complicates implementing a secure network over a wide geographic area since policy data must be coordinated across a large number of devices. Due to this scalability issue, a further need exists to separate the service signaling from data in IP data packets so that policy requests may be more centrally processed.
Another example where a new approach to handling service signaling is needed is in the implementation of Virtual Networks (VNs). A VN includes a group of service users that have specific policies and customized network behavior associated with the group. The policies and behaviors can relate to performance and Quality of Service (QoS) guarantees, routing procedures, addressing, billing, privacy, and to which network services the user has access. Additionally, since issues regarding network resources in a shared use mode versus dedicated use mode are not essential to the concept of a VN, a VN provider may choose any number of ways to implement a VN capability. Due to the diversity of services a VN provider may implement, a need for a new service signal processing architecture exists to efficiently accommodate VN services.